Branched fiber and fibrous composition formed therefrom



Dec. 29, 1970 J TENG 3,551,275

BRANCHED FIBER AND FIBROUS COMPOSITION FORMED THEREFROM Filed Feb. 23, 1967 FI G.6.

INVENTOR 22 James Teng 20 FIG.2.- WX- HM ATTORNEY United States Patent Ofice 3,551,275 Patented Dec. 29, 1970 3,551,275 BRANCHED FIBER AND FIBROUS COMPOSITION FORMED THEREFROM James Teng, Cleveland, Ohio (9530 Carnival Drive, St. Louis, Mo. 63126) Filed Feb. 23, 1967, Ser. No. 618,131 Int. Cl. D02g 3/00; B32b 27/02 US. Cl. 161-170 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates to fibers and especially to fibrous products having increased multi-dimensional strength and stability.

Fibers, synthetic and natural, are useful for a wide variety of purposes. An important use of fibers is in the preparation of textile products, filament compositions, and non-woven fabrics. In such applications, the dimensional strength of the fibrous product is a critical consideration to its utility and commercial value. A great deal of interest thus exists in fibers which are capable of forming fibrous products of enhanced dimensional strength and stability.

An object of this invention, accordingly, is to provide novel fibers.

Another object of this invention is to provide fibers which are suitable for use in the manufacture of fibrous products such as textile compositions, woven fabrics, paper, plastics, ropes, non-woven fabrics, matts, batts, sponges, etc.

Another object of this invention is to provide fibrous products having enhanced stability and strength.

Another object of this invention is to provide nonwoven fibrous compositions.

Another object of this invention is to provide coated or reinforced fibrous compositions.

These and other objects are attained in accordance with this invention by providing a fiber having a multiple of short branches, the average length of the branches being less than about one-tenth that of the extended fiber and being less than about ten times the average distance between the branches. An important aspect of the fibers of this invention is the presence of relatively short branches. The branches may have secondary branches, which are attached to the short branches present on the main chain of the fiber. The branches and secondary branches may be of any physical form, i.e., they may be crimped, straight, curled, looped, undulated, or otherwise irregularly shaped. They may further contain protrusions, scales, or fibrils in various forms such as circular, tubular, or angular forms.

The length of the branches and secondary branches may vary. However, the average length of the branches should not exceed about one-tenth the length of the extended fiber on which the branches are present. Similarly, the average length of the secondary branches should not exceed one-tenth the length of the main chain of the extended fiber. It will be readily approciated that the branches and the secondary branches may be of different lengths. In a preferred embodiment of the invention, a

substantial proportions, usually at least about 20% of the branches and the secondary branches should comprise those having such length. Although there appears to be no minimum limit of the length of the branches and the secondary branches, for practical considerations, such branches should preferably be at least about onefiftieth the length of the extended fiber.

Another important aspect of the invention is the average length of the branches in relation to the average distance between them. It has been found that the average length of the branches should preferably be less than about ten times the average distance between any two branches. In most instances, the average length of the branches is between about one-tenth and two times the average distance between the branches. The diameter or thickness of the fiber and the branches is not critical. For the most part the fiber has a diameter less than about one-hundredth its extended length, and may have a diameter less than about one-ten thousandth its extended length. The diameter of the branches is usually the same as that of the main chain of the fiber, although it may be smaller or larger.

The fiber of this invention may be made from any of the natural or synthetically produced fiber forming substances. Thus, the fiber may be made from polyamides, polyesters, polyolefins, polyvinyl compounds, polyvinyl idene compounds, polyacrylic compounds, polystyrenes, polynitriles, polyurethanes, polysiloxanes, cellulose compounds, glass, etc. as well as a mixture of such compounds. Especially useful are the polyamides such as polymerized caprolactam, poly(omega-aminoundecanoic acid), poly hexamethylene adipamide), poly(hexamethylene sebacamide), poly-esters such as poly (ethylene phthalate), polyurethanes, polyacrylonitriles, and polyolefins such as polyethylenes and polypropylene.

The fibers of this invention can be prepared by a variety of methods. A convenient method involves injecting a fiber-forming resin into a mold of a suitable design for forming the fibers of the desired shape and the resin is then molded into the branched fiber of this invention. Another method involves preparing a fiberforming resinous sheet and feeding the sheet into a cutting press and cutting the sheet with a suitable die so as to form the branched fiber. Still other methods may be used to prepare the branched fiber of the invention.

The following examples illustrate the methods useful for preparing the fibers.

EXAMPLE A A melted nylon (polycaprolactam) molding resin is air-dried at F. to a moisture content of less than 0.05% and then fed into a screw injection machine having a mold of the design as shown in FIG. 1 wherein the two main trunks are perpendicular to each other, the length of each main trunk is 0.5 inch, the diameter of each main trunk and each branch is'0.00075 inch and the average distance between any two branches is 0.05 inch. The resin is then cooled and allowed to solidify to a fiber having segments as shown by FIG. 1.

EXAMPLE B A polyester (terephthalic acid-ethylene glycol polymer) sheet havinga thickness of 0.002 inch is fed into a punching press equipped with a cutting die of the design as shown in FIG. 3, wherein the length of the main trunk is 10 inches, the length of the branches are such as to extend 0.2-0.3 inch from the main trunk, the diameter of the main trunk and the branches is 0.00025 inch.

EXAMPLE C A lime alumina boro silicate glass in molten state is fed into a molding machine having a mold of the design as shown in FIG. 4 wherein the main trunk is 200 inches in length and 0.001 inch in diameter and the branches extend multidirectionally from the trunk and are of such length that they extend 0.1-0.2 inch away from the intersection at which the branches cross the main trunk. The mold is then cooled and the glass is allowed to solidify to a fiber as shown in FIG. 3.

Fibers obtained by the above methods are shown by the figures in the accompanying drawing, described as follows.

FIG. 1 is a plan view of a portion of a fiber having substantially extended trunks.

FIG. 2 is an end view of the portion shown in FIG. 1.

FIG. 3 is a plan view of a portion of another form of the fiber having a substantially straight trunk.

FIG. 4 is a plan view of a portion of another from of the fiber having irregularly crimped trunks.

FIG. 5 is a sectional view of the fiber shown in FIG. 3 taken on the line 55.

FIG. 6 is a sectional view of the fiber shown in FIG. 4 taken on the line 6-6.

With respect to FIG. 1, the branches 22 are joined to the trunks at intersections 24 and the two main trunks having the branches are shown to be substantially perpendicular to each other. Modifications of such fiber include those in which the main trunks are joined at various angles such as 30, 25, 75, 45, etc. and those in which more than two main trunks are joined to each other at a common intersection. A preferred modification consists of fibers which have planar trunks of substantially equal length and diameter and which are joined at a common intersection and extend at substantially the same angles from each other. Such fibers are thus substantially symmetrical and are capable of evenly distributing strains or stress among the trunks. Fibrous compositions such as mats, fabrics, etc. prepared from such symmetrical fibers have unusually high strength and stability.

Further modifications of the fiber may be seen from FIG. 3 in which the branches are shown in various physical forms, and may have secondary branches. For example, the branches 10, which are attached to main trunk 12, are shown in loops, crinkled, branches, etc. In FIG. 4, Sections of main trunk 12 are shown as 12', 12", and 12" which are crinkled and branches 10 may extend in various directions and at various angles from the main trunks 12, 12', 12", and 12".

The form of the fibers in this invention is distinctive over monofilament fibers with a plurality of filament branches distributed along the trunk. The branches of the herein described fiber extend in random angular directions from random sides of the trunk 12, as shown in FIGS. 3-6, and are not limited to substantially one axial plane of the trunk. The present fibers are not limited to a straight trunk; they may be crinkled as shown in FIGS. 4 and 6 at 12, 12, 12", and 12". Where the branches 22 extend in substantially the same plane from the trunk as shown in FIGS. 1 and 2, all the branches are substantially straight; each pair extends coextensively at an inclined angle from the trunk, the crossings being spaced from one another at regular intervals equal to about twice the length of said branches.

As indicated previously, the fibers of this invention are useful for the preparation of a wide variety of fibrous compositions. They are especially desirable for preparing fibrous compositions which have enhanced stability and strength. Such fibrous compositions include, for example, woven fabrics, non-woven fabrics, sponges, paper, cordage, mats, batts, and other textile and products which are customary obtainable from fibers.

The desirability of the fibers of this invention is related to a large extent to its physical form and structure. Thus, the presence of the branches and secondary branches on the fiber is an important consideration to the utility of the fiber. When an array of the fibers is formed, the branches provide and enhance interlocking of the fibers and thus impart unique dimensional strength and stability to the fibrous product. Further, the branches help increase the surface area of the fiber and thus delocalize any strain which may be exerted on the fibrous product. In this regard, it is noted that the number of the branches and their average length have a direct hearing on the ability of the fiber to so impart the strength to a fibrous product. The physical structure or form of the branches likewise affects the utility of the fiber. Fibers having branches which are undulated or contain secondary branches are found to be especially efiective to impart a high degree of dimensional strength and stability to the fibrous product and for this reason, they are preferred for the purposes of this invention.

EXAMPLE 1 A non-woven nylon fibous mat is prepared by blowing the branched nylon fibers of Example A and having the following specifications: average length of the extended fiber 1 /2 inches; average length of the branches, inch; average distance between 4; diameter of the fiber, inch into a conveyor and then a stitching machine whereby a fibrous mat is formed.

EXAMPLE 2 A non-woven fibrous mat is prepared by the process of Example 1 except that a fibrous mixture of the branches nylon fibers and glass fibers (having some specifications) (ratio of the number of the nylon fibers to glass fibers being 1:9) is used in place of the nylon fibers.

EXAMPLE 3 A homogeneous mixture of 1 part (by weight) of the branched fibers having the form shown in FIG. 1 and prepared by the procedure of Example B and 2.5 parts of viscose rayon is made into a web by means of a webbing machine.

EXAMPLE4 A reinforced paper is prepared by blending a sulfate paper pulp and branched cellulose diacetate fibers made by the process of Example A and forming a sheet by the procedure described in (APP) Standard T205 M58.

EXAMPLE 5 A mixture of straight glass fibers (length, 2.5 inches and diameter, 0.02 inch) and branched glass fibers made by the process of Example A (weight ratio of the straight fibers to the branched fibers being 100:1) is blown onto a moving belt to a thickness of 0.05 pound of glass per square foot. The mass is then treated with water to compact the fielt of fibers. The wet felt is treated with a fine spray of molten asphalt so as to saturate the fielt uninformly with asphalt (20% by weight of the glass fibers). The felt is heated to evaporate the water therefrom. The resulting product is a reinforced asphalt-fibrous mat having increased dimensional strength and stability. The mat is useful as a roofing material.

EXAMPLE 6 A homogeneous mixture is prepared by bleeding of chopped lime alumina borosilicate glass strands (0.0005 inch in diameter and 0.75 inch in length) and 20% of the branched fiber strands of this invention (0.75 inch is main trunk length, 0.001 inch in diameter in the form as shown in FIG. 3 having branches each being of 0.05 inch in length and 0.001 inch in diameter and separated by an average distance between any two branches of 0.1 inch; as shown by FIG. 2). A laminate composition prepared by mixing the above fibrous mixture and a commercial polyester (polyethylene terephthalic) molding composition is placed in a heated mold for cafeteria trays and the mold is heated at 150 F. and psi. for 4 minutes until curing is completed. A finished reinforced tray is thus obtained. Other products such as boat hulls,

automobile bodies, laundry tubs, luggages and other reinforced fibrous products can be obtained by replacing, in any of the well-known methods, a portion such as from 1%, 20%, 50%, or 75% or all of the conventional fibrous component with the fiber of this invention. Similarly, the fiber of this invention can be used as a substitute for a part or all of the fibrous component in other fibrous products such as woven or non-woven fabrics, paper, mats, and other textile products. Such products can be made by any of the techniques known in the art such as is described in Modern Plastics Encyclopedia, McGraw Hill; 1965, Molding Reinforced Plastics; Fibrous Glass Reinforcements, Laminates and Reinforced Plastics, etc.

What is claimed is:

1. A branched fiber having at least two main trunks joined together proximate their midpoints in substantially perpendicular relationship to each other, each of said trunks having a multiple of short branches extending therefrom, the average length of said branches being less than about one-tenth that of the extended main trunks and being less than about ten times the average distance between the branches.

2. A fibrous composition comprising an array of the branched fibers of claim 10.

3. A fibrous composition comprising an array of straight fibers and from about 1% to about 50% of the branched fibers of claim 10.

4. A molding composition comprising a moldable resin and the branched fibers of claim 10.

5. A molding composition comprising a moldable plastic composition and the branched fibers of claim 10.

6. A reinforced fibrous composition comprising a molded plastic and the branched fibers of claim 10.

References Cited UNITED STATES PATENTS 3,503,199 3/1910 Nesbitt-Dufort 161177X 3,121,656 2/1964 Gluck 1 6l169 3,243,339 3/1966 Scragg et al. 16l179 3,253,072 5/1966 Scraggs et al. 264Fib. Dig. 3,336,174 8/1967 Dyer et al. 264--Fib. Dig. 3,199,284 8/1965 Scragg 161Fib. Dig.

ROBERT F. BURNETT, Primary Examiner R. O. LINKER, 111., Assistant Examiner U.S. CL. X.R. 16l179 

